I've had this nagging question which might sound stupid, but when a lighting fixture is rated for a given number of watts, does that take into account energy efficient bulbs?

For example, let's say you have a fixture that calls for 60W maximum bulbs. Is it acceptable to install one of those energy efficient bulbs that uses say 23W actual, but produces the equivelant of 100W of lighting? In other words, are you being limited by wattage or lighting output when a fixture calls for a given wattage? Is heat itself the issue, or is conductor size and material type the limiting factor with respect to fixture wattages... or both?

I can't seem to find anything code related in this area, and manufacturers don't seem to address it either.

So if a customer likes a certain light fixture that only uses maximum 60W bulbs, but it doesn't produce enough light for their tastes, can we sell them on using lower wattage, brighter energy efficient bulbs in the case?

This has been a nagging question everytime I see one of those stickers on fixtures.

Joe